#include<iostream>
#include<vector>
#include<string>
using namespace std;

bool cmp(vector<int>&A , vector<int>& B)
{
    if(A.size() != B.size()) return A.size() > B.size();
    for(int i = A.size() - 1 ; i >= 0 ; i --)
        if(A[i] != B[i]) return A[i] > B[i];
    return true;
}

vector<int> sub(vector<int>& A,vector<int>& B)
{
    vector<int> C;
    for(int i = 0 ,t = 0 ; i < A.size();i++)
    {
        t = A[i] - t;
        if(i < B.size()) t -= B[i];
        C.push_back((t+10) % 10);
        if(t < 0) t = 1;
        else t = 0;
    }
    while(C.size() > 1 && C.back() == 0) C.pop_back();
    return C;
}

int main()
{
    string a, b;
    vector<int> A,B,C;
    cin >> a >> b;
    for(int i = a.size() - 1; i >= 0 ;i--)A.push_back(a[i]-'0');
    for(int i = b.size() - 1; i >= 0; i--)B.push_back(b[i]-'0');
    if(!cmp(A,B))
    {
        cout << "-";
        C = sub(B,A);
    }else C = sub(A,B);
    
    for(int i = C.size() - 1; i >= 0 ; i--) cout << C[i];
    cout << endl;
    return 0;
}